Large-scale spatial and interspecies differences in trace elements and stable isotopes in marine wild fish from Chinese waters

https://doi.org/10.1016/j.jhazmat.2012.02.032Get rights and content

Abstract

We conducted a large scale investigation of twelve trace element levels and stable isotopes (δ13C and δ15N) in twenty-nine marine wild fish species collected from Chinese coastal waters. Trace element levels varied significantly with species. Clear spatial variations were found for Al, As, Cd, Cr, Fe, Ni, and Pb, whereas Ag, Cu, Mo, Se and Zn did not show much spatial variation. The Pearl River Estuary contained the highest concentrations of Al, Cr, Ni, and Pb, whereas the most southern waters (Haikou) contained the lowest concentrations of Al, Fe, and Pb. There was no correlation between log-transformed trace elements concentrations and δ15N values or δ13C values, indicating no biomagnification among these trace elements. The calculated hazard quotients (HQ) of 10 elements were less than 1, thus there was no obvious health risk from the intake of trace elements through marine wild fish consumption.

Highlights

► A large-scale study on trace element levels in marine wild fish from Chinese waters. ► Spatial variation found for Al, As, Cd, Cr, Fe, Ni, Pb, but not for Ag, Cu, Mo, Se and Zn. ► The Pearl River Estuary contained the highest concentrations of Al, Cr, Ni, and Pb. ► No biomagnification occurred for any of the trace elements studied in marine fish. ► No obvious health risk from the intake of trace elements through fish consumption.

Introduction

With the recent very rapid development of industry and agriculture in China, a large number of harmful substances have been discharged into the sea, resulting in coastal water pollution. These substances are often persistent and have potentials of being bioaccumulated by the marine organisms. In a most recent review of trace metal pollution in estuarine and coastal waters of China, Pan and Wang [1] concluded that industrial and domestic sewage discharges, mining, smelting, and e-wastes recycling are the important sources contributing to coastal pollution in China. Metal contamination in the coastal environments is closely associated with accelerated economic growth in the past decades. Various compartments such as sediments, water and organisms collected from the heavily industrialized areas often contained alarmingly high metal concentrations. Such elevated levels of metal contamination along China's coastal environment can increase the risk of metal exposure to humans by seafood consumption.

Fish are the major seafoods consumed by humans. FAO [2] estimated that about 75% (105.6 million tons) of worldwide fish production were directly consumed by human in 2004 alone. In the China Seas, there are a variety of marine species and outputs, but all of these marine fish species are currently under serious threats. Levels of contaminants in fish are of particular interests due to their potential risks to humans. Numerous studies have measured the trace elements levels in different species of edible fish worldwide [3], [4], [5], [6], [7]. Several earlier studies in China reported trace elements contamination in seawater, sediments, and bivalves [1], with only few focusing on marine fish [8], [9], [10].

This study represents the first large-scale investigation of multi-elemental accumulation in marine wild fish from China Seas. We targeted the analysis of twelve trace elements (Ag, Al, As, Cd, Cr, Cu, Fe, Mo, Ni, Pb, Se, and Zn) in their muscle tissues. Mercury was not specifically analyzed in this study, despite the fact that it is probably the most important in terms of human health exposure assessment. The marine wild fish were caught from seven main coastal areas from Northern to Southern parts of China. We also collected the marine wild fish from the Pearl River Estuary, the second largest estuary in China. With the establishment of many industrial developmental zones along the coastal cities, estuaries are especially vulnerable to metal pollution due to uncontrolled release of industrial effluents. The main objectives of this study were to examine whether the marine wild fish were contaminated with trace elements, and to test whether there were any spatial or interspecific variations in the coastal or estuarine environment. Health risk assessment was then conducted to evaluate whether these marine wild fish presented any potential risk to humans as a result of consumption. From a public health perspective, this study could provide consumers with better knowledge of contamination problems associated with seafood consumption. In addition, we also used the stable isotope approach (δ13C and δ15N) to estimate the relationships among concentrations of trace elements, food sources and trophic levels of fish species.

Section snippets

Sampling

Twenty-nine marine wild fish species of similar sizes were collected from eight stations along the coastal areas in China, including seven main coastal cities (Qinhuangdao, Dalian, Qingdao, Shanghai, Huilai, Zhanjiang and Haikou) and the Pearl River Estuary (Fig. 1), between April and May 2010. Each species were represented by 10–20 individuals, with a body length of approximately 10 cm. The collected samples were transferred to the laboratory and rinsed with distilled water three times. The

Geographic variation of metal concentrations

The concentrations of 12 trace elements in fish collected along the Chinese coastal waters are shown in Table 1. Differences of trace elements concentrations in different fish and from different locations are described below.

The Ag concentrations in the fish were generally very low (0.38–7.52 ng/g) among all the locations. Several species of fish had their tissue Ag concentrations lower than the limit of quantitation (LOQ) or method detection limit (MDL) (0.1 ng/L). There was no clear spatial

Geographic variance

Earlier studies largely reported trace elements concentrations in marine fish based on wet weight. Table 3 compares the trace elements concentrations in marine fish collected from different locations of the world. A wet/dry weight conversion factor of 4 can be used for easy comparison [7].

Among the 12 trace elements quantified in this study, Ag, Cu, Mo, Se, and Zn had no clear spatial differences among all the locations (from Northern to Southern parts). Several possibilities may explain such

Conclusion

Accumulation of trace elements (such as Al, As, Cd, Cr, Ni, Pb) in food is a major safety health concern worldwide. The present study involved a large scale investigation of trace elements in marine wild fish in China Seas. The data indicated that trace elements levels had geographic differences, likely due to the differences of trace elements bioaccumulation and the sources of industrial and agriculture inputs. The distribution trend revealed the current economic status of development from the

Acknowledgments

We thank the anonymous reviewers for their helpful comments. This work was supported by the CAS (Chinese Academy of Sciences)/SAFEA (State Administration of Foreign Experts Affairs) International Partnership Program for Creative Research Teams (KZCX2-YW-T001) and the Innovation Group Project of Chinese Academy of Sciences (KZCX2-YW-Q07).

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